Grammar · N4
〜ておく: do something in advance
Prepare for later or leave something in a useful state.
In short
Verb て-form + おく often means performing an action ahead of time because it will be useful later. In casual speech, ておく can contract to とく after some verbs.
How it works
旅行の前にホテルを予約しておきます means booking before the trip as preparation.
Useful contrast
It can also mean leaving something as it is, depending on the verb and context.
Examples
明日のために準備しておきます。
I will prepare in advance for tomorrow.
窓を開けておいてください。
Please leave the window open.
Common pitfall
The key idea is future usefulness or maintained state, not simply “do and then”.